One of the most popular forms of baked goods are so-called "dry cereal products"; namely, baked products which have low water concentrations and are, therefore, crispier than soft products such as bread or cake. As used herein, the term "dry cereal products" refers to baked products made from grain, such as crispbread, biscuits, rusk, breadcrumbs, sour crispbread, crackers, baked snacks, waffles, cookies, pretzels, ice cream cones and dark bread.
Dry cereal products have a longer shelf life and can be distributed over wide geographic areas in contrast to soft products which are highly perishable and are typically distributed on a more local basis. Dry product processes tend to be larger and more intricate--and often more automated--as a result.
A bottleneck in the production process of dry cereal products, such as crispbread, biscuits, sour crispbread, and dark bread, etc. is often the limited production capacity of ovens used, but increasing oven size requires high capital investment. Attempts have also been made to improve the process efficiency by using flour with a low water-binding capacity and by other apparatus improvements. Such expedients, however, have generally been inadequate.
In an industrial production process of dry cereal products, such as crispbread and biscuits, the ingredients (flour, liquid, requisite additives, such as salt, sugar, dough raising agents and possible spices) are mixed into a dough. A thin dough cake is baked rapidly at a high, accurately programmed temperature, and dried. The moisture content of the final product is extremely important and will vary depending on the product involved. In many instances, the crispness and preservation properties are maximized at a moisture content of between about 7% and about 9% by weight. On an average, the crispness of biscuits is at best at a moisture content of less than 4% by weight. In addition to water content, the crispness and preservation properties of biscuits and other products are affected by other factors, such as fat content. For example, the protein content of flour used in baking semi-sweet biscuits is of great importance for the crispness of the final product.
The quality of flour to be used in a dry bread product depends on the product to be prepared. In crispbread production, whole rye flour is used in most cases; however, the popularity of wheat crispbread is on the increase. Most biscuits are made of wheat, while the demand and consumption of oatmeal biscuits and especially of rye biscuits are insignificant.
The most important flour properties are those affecting the crumb structure, crispness and volume. With doughs raised with yeast, the "falling" number required for rye flour ranges from 120 to 200. (The "falling" number is measured by procedures well known and defined in the prior art.) The falling number of rye flour to be used in a dough raised by whipping gas into the dough (so called "ice bread") should also be relatively high. Sour, thick crispbread can be made from rye flour having a lower falling number, because the acidity prevents the inherent enzymes of flour from decomposing starch too far. The falling number of flour used in the production of biscuits should be high (more than 300) due to, e.g., their long production process and the rather high temperature of dough water in the production of semi-sweet biscuits, for instance.
Flour used in the production of crispbread usually has a relatively low protein content, generally varying between 8 and 12% by weight. The water-binding capacity of such flour is not as high as that of flour rich in protein, so less energy is required for drying during baking. In biscuit baking, protein content is of vital importance to the quality of flour and that of the product. The protein content of the flour should range from 7.5% to 10.5% by weight on dry substance. Flour having a protein content less than 10% by weight is best suited for baking semi-sweet biscuits.
Yeast or a chemical raising agent can be used for proofing. Proofing can also be effected by mixing gaseous substances into the dough.
In the production of both crispbread and biscuits, water or milk is used as dough liquid. In the production of crispbread, the amount of liquid needed is nearly equal to that of flour, that is, the dough is considerably softer than in the production of normal soft bread. In biscuit production, less liquid is usually needed than in the production of crispbread. The use of large amounts of liquid requires long baking times and large amounts of energy at the baking stage to reduce the water concentration of the final product to an acceptable level.
In a dry cereal product production process, the amount of dough liquid is in most cases determined by the technical qualities of the process and the apparatus. For example, the softness of a dough suitable for use in a crispbread production process and, as a consequence, the amount of liquid needed is determined on one hand by the mechanical strength of the blades of the dough mixer and on the other hand the operation of the pricking device. In addition, the webforming ability sets certain requirements on the softness of dough. Dough softness is described by a consistency value. (Consistency is measured by a penetrometer by allowing the measuring cone of the penetrometer to fall into the dough for 10 seconds, whereby the penetration of the cone in millimeters gives the consistency of the dough; the greater the value, the softer the dough. A penetrometer is a standard piece of equipment well known in the baking art.)
The crispness, taste, and machinability of crispbreads and biscuits can be increased by the use of fat and sugar.
In crispbread production, the dough is formed into a weblike mat after suitable proofing. The mat can be baked as such, or it can be cut or chopped into separate cakes, or the mat is formed into separate cakes by means of moulds, rolls, and the like. The cakes can be patterned before baking, e.g., by pricking. Pricking provides the product with a pattern typical of it, and binds the surface layers of the cake together. If necessary, the final proofing of the products is carried out after the patterning, whereafter the products are baked. So called "ice bread" is not proofed at this stage; it is baked immediately after the pricking.
Biscuits, such as semi-sweet biscuits, are often made by so-called "all-in" (or "straight") dough making process, in which the dough is prepared by mixing all the dry ingredients simultaneously with the dough liquid and other liquid ingredients. The way in which the dough is prepared is of great importance in the production of semi-sweet biscuits. As semi-sweet biscuits should possess an extensible gluten network, relatively high dough temperatures, about +40.degree. C., are desirable in the dough preparation phase. An example of a mixer suitable for the production of biscuits is a horizontal two-blade mixer standard in the baking industry. After preparation, the dough should be allowed to stand so that the dough liquid is absorbed in the dry ingredients (floor time). After the floor time the dough is moulded, e.g., by means of a four-roll feeder and then folded by passing it through a pair of rolls. After folding the dough is passed through sheeting rolls. Sheeted dough is pricked and cut with a roll cutter (drum cutter).
The products lose moisture concentration during baking. The moisture content of a conventional finished crispbread product is about 7% to about 12% by weight. The moisture content of product raised with gas may be as low as about 2% by weight. On an average, the moisture content of biscuits does not exceed about 4% by weight.
To achieve the desired final moisture consent, the baked product usually has to be dried further. The drying can be effected by using a convection oven, basket conveyors transported above the oven in the waste heat, "after-baking", that is, drying in a tunnel oven, or dielectric drying. If necessary, the baked product can be chopped, e.g., by sawing.
It is known that cellulolytic/hemicellulolytic enzymes cleave non-starch polysaccharides present in flour. Addition of cellulolytic and/or hemicellulolytic enzymes has been used to improve the properties of the baking process and the finished baking product.
Japanese Patent Application No. 5701/1968 describes a method of improving the quality of white sour bread by adding to the dough an enzyme composition having cellulolytic and/or hemicellulolytic activity. It is emphasized in the patent application that the addition of the enzyme composition causes decomposition of fibrous components present in flour, such as cellulose and pentosans, the presence of which as such would considerably deteriorate the quality of bread by rendering the dough inhomogeneous and by preventing the formation of gluten. It is recited that the addition of cellulolytic/hemicellulolytic enzymes provides soft bread with increased volume, more uniform grain structure and slower ageing than bread prepared with prior art methods.
Finnish Patent Application No. 881905 (U.S. application Ser. No. 341,389 filed Apr. 21, 1989, now U.S. Pat. No. 4,990,343 describes the use of cellulolytic/hemicellulolytic enzymes in combination with glucose oxidase or glucose oxidase and sulphydryl oxidase in baking soft bread from wheat and rye flour. These enzymes are used for optimizing the baking process. Moreover, it has been found that the enzyme combinations improve the rheological properties, gluten, processability, and tolerance of a flour dough. It has also been found to improve the volume, grain structure and anti-staling properties of a bakery product.
However, because of the significant differences in the process for baking dry cereal products (such as crispbread, etc.) and the increased moisture content of dough used to bake these products, enzyme treatment of dough for dry cereal products has heretofore not been utilized. It has now been found according to the present invention that an addition of cellulolytic and/or hemicellulolytic enzymes increases the process capacity in the production of dry cereal products. Unexpectedly and surprisingly, the enzyme addition of the invention makes the dough softer, so less dough liquid is required as compared with conventional techniques. The reduced concentration of water requires less energy than prior art methods for baking the product and the need for after-drying is decreased or eliminated. In large scale baking processes, this improved efficiency will result in substantial cost savings.
In addition, the final product obtained by the method of the invention has a lower shrinkage and increased crispness.